Modal dialogs stay on the back of other windows on Opensuse

Question

In my application, there are dialog screens written by java SWT. When a modal dialog (warning/error/file dialog etc.) is opened, it can not stay on top of the parent screen after clicking the parent screen, or it is opened behind of the main screen. The dialog can only be opened by pressing ALT+tab. This problem occurs on Opensuse 11.04. It does not occur on Windows.

Main and ShellExample classes are to test the problem. When you press the "open modal dialog" button in the openning shell, FileDialog comes behind. MessageDialog is opening at the top, but when clicking the shell, it goes to back.

Here is Main class;

public class Main {

    /**
     * @param args
     */
    public static void main(String[] args) {
        // TODO Auto-generated method stub

        Display display = new Display();
        final Shell shell = new Shell(display);

        shell.setLocation(0,0);
        shell.setSize(500, 500);

        shell.setLayout(new GridLayout());
        FormToolkit  toolkit = new FormToolkit(shell.getDisplay());

        Button okButton = toolkit.createButton(shell, "  Open Shell  ", SWT.NONE);

        okButton.addSelectionListener(new SelectionAdapter() {
            public void widgetSelected(SelectionEvent e) {
                ShellExample mainDialog = new ShellExample(shell);
                mainDialog.open();
                }
          });

        shell.open();

        while (!shell.isDisposed()) {
          if (!display.readAndDispatch()) {
            display.sleep();
          }
        }
        display.dispose();

    }
}

and this is ShellExample class;

public class ShellExample extends Dialog {

    private Shell shell;
    public ShellExample(Shell parent) {
        super(parent, SWT.NO_TRIM | SWT.PRIMARY_MODAL);
        // TODO Auto-generated constructor stub
    }

    public Object open() {

        // TODO Auto-generated method stub
        shell = new Shell(getParent(), getStyle());
        createContents();

        shell.open();
        shell.layout();


        Display display = getParent().getDisplay();
        while (!shell.isDisposed()) {
            if (!display.readAndDispatch()) {
                display.sleep();
            }
        }   
        return null;

    }

    private void createContents() {
        // TODO Auto-generated method stub

        GraphicsEnvironment ge = GraphicsEnvironment.getLocalGraphicsEnvironment();
        shell.setSize(ge.getMaximumWindowBounds().width,ge.getMaximumWindowBounds().height);

        shell.setText(getText());
        shell.setLayout(new FillLayout());

        shell.setLayout(new GridLayout());
        FormToolkit  toolkit = new FormToolkit(shell.getDisplay());


        Button okButton = toolkit.createButton(shell, " open modal dialog ", SWT.NONE);

        okButton.addSelectionListener(new SelectionAdapter() {
            public void widgetSelected(SelectionEvent e) {
                FileDialog fd = new FileDialog(shell, SWT.SAVE);
                fd.setText("file dialog");
                fd.open();
             // MessageDialog.open(MessageDialog.WARNING  , shell, "warning_title", "warning_message", SWT.APPLICATION_MODAL);
            }
          });

    }
}

Any suggestions?

Thanks.

Answer 1

In Linux, it is up to the window manager (Gnome, KDE, XFCE, Enlightenment, etc) to implement this behavior. I know that several Linux Window Managers particularity enlightenment and the tiling window managers do not honor modal windows. To find out if what you are trying to do is even possible you should look at the documentation for the window manager you are using to see if it supports it. This can be found by looking at the NET_WM flags the one you are probably looking for is _NET_WM_STATE_MODAL some documentation about this can be found on the Free Desktop Standards website, the latest spec at the time of writing is http://standards.freedesktop.org/wm-spec/wm-spec-1.5.html